Secondary part for linear motor with a cooling system

ABSTRACT

The invention relates to a secondary part for a linear motor, comprising several permanent magnets ( 3 ) which are juxtaposed and embedded in a cast body ( 5 ) of plastic compound on a carrier plate ( 1 ). According to the invention, longitudinal grooves are provided alongside the juxtaposed permanent magnets ( 3 ) in the cast body ( 5 ) to receive cooling pipes ( 9 ). The grooves are preferably configured as undercut grooves and form locking means for securing the cooling pipes ( 9 ). The inventive measures are particularly useful for forming secondary parts from several juxtaposed secondary part elements, whereby single-piece cooling pipes can be used for all of the segments.

[0001] The invention relates to secondary parts for linear motors, inparticular synchronous linear motors.

[0002] Such linear motors include a primary part in which several coilsare placed in linear arrangement, and a secondary part, in which severalpermanent magnets are placed in linear arrangement in accordance withthe pole pitch measure of the primary part. The primary part is fed withelectric energy and interacts with the secondary part via an air gap.

[0003] In operation, a portion of the electric energy in the primarypart is converted into heat, and it is known to cool the primary partvia cooling coils, whereby the cooling coils are normally attached onthe coils-distal side of the primary part.

[0004] The secondary parts normally include a metallic carrier plate onwhich the permanent magnets are arranged, wherein the permanent magnetscan be embedded in a casting compound (DE-A-19936064).

[0005] In operation, the secondary parts also heat up, whether as aresult of electromagnetic interaction with the primary part, or whetheras a result of heat radiation from the primary part onto the secondarypart.

[0006] Although, it is possible to attach also a cooling pipe upon themetal plate of the secondary part; this, however, requires complicatedassembly steps for securing the cooling pipe and possibly drillingand/or milling operations on the carrier plate.

[0007] It is therefore the object of the invention to provide asecondary part or a secondary part element for a linear motor, which canbe provided in a simple manner with a cooling device.

[0008] This object can be attained by a secondary part element accordingto the features of claim 1, and by a secondary part according to claim5; the dependent claims set forth advantageous configurations of theinvention.

[0009] According to the invention, it is proposed to providelongitudinal grooves in the cast body of the secondary part forreceiving the cooling pipes. These longitudinal grooves can be realizedin a simple manner during casting of the secondary part, withoutrequiring further finishing works upon the carrier plate of thesecondary part.

[0010] The grooves extend hereby preferably at a depth up to the surfaceof the carrier plate in order to establish at least a mechanical contactbetween cooling pipes, which are placed into the grooves, and thesurface of the carrier plate.

[0011] Preferably, the grooves have a cross section which corresponds atleast partially to the cross section of the cooling pipes, and thegrooves have undercuts so that the undercuts form locking means for thecooling pipes. In this case, the cooling pipes are only required to be“clasped” into the grooves, i.e. they snap into the grooves, withoutrequiring additional fasteners.

[0012] The arrangement according to the invention is especially suitablefor secondary parts which are composed of several secondary partelements. In this case, the grooves are arranged in alignedrelationship, and single-piece cooling pipes can be placed in allgrooves of the juxtaposed segments.

[0013] An exemplified embodiment of the invention will now be describedwith reference to the attached drawings, in which:

[0014]FIG. 1 shows a cross section of a secondary part element;

[0015]FIG. 1a shows a detailed cross section, and

[0016]FIG. 2 shows a top view of a secondary part of two secondary partsegments.

[0017] As shown in FIGS. 1 and 2, permanent magnets 3 are placed inlinear arrangement in a manner known per se on a carrier element 1 ofmagnetizable material.

[0018] The permanent magnets 3 are cast in a cast body 5 cast onto thecarrier plate 1, wherein the carrier plate is provided with fasteningbores 7 for securement of the secondary part, and respective recesses 7′are provided in the cast body.

[0019] In the area between the recesses 7′ and the permanent magnets 3,the cast body includes grooves which extend alongside the juxtaposedarrangement of the magnets along the secondary part elements. Thelongitudinal grooves are so configured as to form-fittingly receivecooling pipes 9 at least over a portion of its cross section.

[0020] In the event of a round cross section for the cooling pipes 9, apossible configuration of the grooves is illustrated in FIG. 1a.

[0021]FIG. 1a shows hereby a partially circular groove 15 in the castbody 5 with undercuts 13.

[0022] As can be further seen from FIG. 1a, the groove has a depth whichpreferably extends up to the surface of the carrier plate 1, so that acooling pipe, placed (snapped) into the groove, is in mechanical contactwith the carrier plate at least linearly.

[0023] The arrangement according to the invention is especially suitablefor secondary parts which are comprised of several secondary partelements. This is shown, in particular, in FIG. 2, which depicts twosecondary part elements I, II. The secondary part elements are herebyarranged such that the grooves are aligned with one another, andsubsequently, the cooling pipes are snapped into the grooves and held inplace by the undercuts 13. Cooling is implemented by supplying coolantto the cooling pipes via an inlet Z, whereby the coolant passes by thesecondary part elements 1, 11 and exits via an outlet A.

[0024] Although the casting compound, such as polyurethane or epoxyresin, represents in principle a poor heat conductor, still, theproposed configuration has significant advantages compared toalternative solutions.

[0025] It could be conceivable to provide the bottom of the carrierplate 1 with recesses 11 for receiving cooling pipes. This, however, asstated above, requires cumbersome manipulations. Moreover, theserecesses are arranged remote to the permanent magnets 3 and distal tothe primary part as heat source; thus, heat has to pass the entirethickness of the carrier plate.

[0026] It is also conceivable to provide the fastening elements (notshown) with recesses 7′, 7 to secure a cooling pipe. This, too, has theproblem that the cooling pipe is arranged distal to the permanentmagnets and to the heat source primary part, so that heat has topenetrate the carrier plate as well.

[0027] In contrast thereto, the invention ensures that the cooling pipes9 are at least in linear contact with the carrier plate 1, namelydirectly next to the permanent magnets 3. Moreover, the grooves 15 areopen toward the air gap so that the cooling pipes 9 are exposed indirection of the heat source primary part and thus are able to directlyabsorb heat radiation from the primary part.

1. Secondary part element for a linear motor with a carrier plate (1)for support of several permanent magnets (3), wherein the permanentmagnets (3) are embedded in a cast body (5) upon the carrier plate (1),characterized in that the cast body (5) has longitudinal grooves (15)for receiving cooling pipes (9).
 2. Secondary part element according toclaim 1, characterized in that the grooves (15) have a depth extendingup to the surface of the carrier plate (1).
 3. Secondary part elementaccording to claim 1 or 2, characterized in that the grooves (15) haveundercuts (15).
 4. Secondary part element according to one of the claims1 to 3, characterized in that the undercuts (13) have locking means. 5.Secondary part comprised of several juxtaposed secondary part elements(I, II) according to one of the preceding claims, characterized in thatthe grooves (15) are arranged in aligned relationship, and single-piececooling pipes (9) are received in the aligned grooves (15).